Superabrasive elements and methods for processing and manufacturing the same using protective layers

ABSTRACT

A method of processing a polycrystalline diamond element includes forming a protective layer over a selected portion of a polycrystalline diamond element, the polycrystalline diamond element having a polycrystalline diamond table that includes a superabrasive face, a superabrasive side surface, and a chamfer extending between the superabrasive face and the superabrasive side surface. A portion of the superabrasive side surface is covered by the protective layer and the protective layer is not formed over the chamfer. The method includes exposing at least a portion of the polycrystalline diamond element to a leaching solution. A polycrystalline diamond element has a polycrystalline diamond table that includes a leached volume extending from the superabrasive face to a portion of the chamfer proximate to the superabrasive side surface, and the leached volume does not substantially extend along the superabrasive side surface.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/555,715, titled “Superabrasive Elements and Methods for Processingand Manufacturing the Same Using Protective Layers” and filed 8 Sep.2009, the disclosure of which is hereby incorporated, in its entirety,by this reference.

BACKGROUND

Wear-resistant, superabrasive materials are traditionally utilized for avariety of mechanical applications. For example, polycrystalline diamond(“PCD”) materials are often used in drilling tools (e.g., cuttingelements, gage trimmers, etc.), machining equipment, bearingapparatuses, wire-drawing machinery, and in other mechanical systems.Other types of superabrasive materials, such as ceramics (e.g., cubicboron nitride, silicon carbide, and the like), may also be utilized forsimilar applications.

Conventional superabrasive materials have found utility as superabrasivecutting elements in rotary drill bits, such as roller cone drill bitsand fixed-cutter drill bits. A conventional cutting element may includea superabrasive layer or table, such as a PCD table. The cutting elementmay be brazed, press-fit, or otherwise secured into a preformed pocket,socket, or other receptacle formed in the rotary drill bit. In anotherconfiguration, the substrate may be brazed or otherwise joined to anattachment member such as a stud or a cylindrical backing. Generally, arotary drill bit may include one or more PCD cutting elements affixed toa bit body of the rotary drill bit.

Conventional superabrasive materials have also found utility as bearingelements in thrust bearing and radial bearing apparatuses. Aconventional bearing element typically includes a superabrasive layer ortable, such as a PCD table, bonded to a substrate. One or more bearingelements may be mounted to a bearing rotor or stator by press-fitting,brazing, or through other suitable methods of attachment. Typically,bearing elements mounted to a bearing rotor have superabrasive facesconfigured to contact corresponding superabrasive faces of bearingelements mounted to an adjacent bearing stator.

Cutting elements having a PCD table may be formed and bonded to asubstrate using an ultra-high pressure, ultra-high temperature (“HPHT”)sintering process. Often, cutting elements having a PCD table arefabricated by placing a cemented carbide substrate, such as acobalt-cemented tungsten carbide substrate, into a container orcartridge with a volume of diamond particles positioned on a surface ofthe cemented carbide substrate. A number of such cartridges may beloaded into a HPHT press. The substrates and diamond particle volumesmay then be processed under HPHT conditions in the presence of acatalyst material that causes the diamond particles to bond to oneanother to form a diamond table having a matrix of bonded diamondcrystals. The catalyst material is often a metal-solvent catalyst, suchas cobalt, nickel, and/or iron, that facilitates intergrowth and bondingof the diamond crystals.

In one conventional approach, a constituent of the cemented-carbidesubstrate, such as cobalt from a cobalt-cemented tungsten carbidesubstrate, liquefies and sweeps from a region adjacent to the volume ofdiamond particles into interstitial regions between the diamondparticles during the HPHT process. The cobalt may act as a catalyst tofacilitate the formation of bonded diamond crystals. A metal-solventcatalyst may also be mixed with a volume of diamond particles prior tosubjecting the diamond particles and substrate to the HPHT process.

The metal-solvent catalyst may dissolve carbon from the diamondparticles and portions of the diamond particles that graphitize due tothe high temperatures used in the HPHT process. The solubility of thestable diamond phase in the metal-solvent catalyst may be lower thanthat of the metastable graphite phase under HPHT conditions. As a resultof the solubility difference, the graphite tends to dissolve into themetal-solvent catalyst and the diamond tends to deposit onto existingdiamond particles to form diamond-to-diamond bonds. Accordingly, diamondgrains may become mutually bonded to form a matrix of polycrystallinediamond, with interstitial regions defined between the bonded diamondgrains being occupied by the metal-solvent catalyst. In addition todissolving carbon and graphite, the metal-solvent catalyst may alsocarry tungsten, tungsten carbide, and/or other materials from thesubstrate into the PCD layer of the cutting element.

The presence of the metal-solvent catalyst and/or other materials in thediamond table may reduce the thermal stability of the diamond table atelevated temperatures. For example, the difference in thermal expansioncoefficient between the diamond grains and the solvent catalyst isbelieved to lead to chipping or cracking in the PCD table of a cuttingelement during drilling or cutting operations. The chipping or crackingin the PCD table may degrade the mechanical properties of the cuttingelement or lead to failure of the cutting element. Additionally, at hightemperatures, diamond grains may undergo a chemical breakdown orback-conversion with the metal-solvent catalyst. Further, portions ofdiamond grains may transform to carbon monoxide, carbon dioxide,graphite, or combinations thereof, thereby degrading the mechanicalproperties of the PCD material.

Accordingly, it is desirable to remove a metal-solvent catalyst from aPCD material in situations where the PCD material may be exposed to hightemperatures. Chemical leaching is often used to dissolve and removevarious materials from the PCD layer. For example, chemical leaching maybe used to remove metal-solvent catalysts, such as cobalt, from regionsof a PCD layer that may experience elevated temperatures duringdrilling, such as regions adjacent to the working surfaces of the PCDlayer.

Conventional chemical leaching techniques often involve the use ofhighly concentrated and corrosive solutions, such as highly acidicsolutions, to dissolve and remove metal-solvent catalysts frompolycrystalline diamond materials. However, in addition to dissolvingmetal-solvent catalysts from a PCD material, leaching solutions may alsodissolve portions of a substrate to which the PCD material is attached.For example, highly acidic leaching solutions may dissolve portions of acobalt-cemented tungsten carbide substrate, causing undesired pittingand/or other corrosion of the substrate surface.

In some conventional leaching techniques, a polymeric shielding cup maybe placed around a portion of a PCD element to protect the substratefrom a leaching solution. However, a leaching solution may occasionallypass through spaces existing between the shielding cup and the PCDelement, particularly when the PCD element is immersed in the leachingsolution for extended periods of time and/or when the PCD element issubjected to changing temperatures and/or pressures.

Accordingly, conventional shielding cups may only provide PCD articleswith limited protection from leaching solutions, and such shielding cupsmay not provide adequate protection under various leaching conditionsthat are required in order to leach interstitial materials from the PCDarticles to a desired degree. For example, in order to leach PCDarticles to certain leach specifications, the PCD articles may beexposed to leaching solutions for extended periods of time and/or thePCD articles may be exposed to the leaching solutions under varioustemperature and/or pressure conditions. Additionally, conventionalshielding cups may not provide adequate protection to PCD articleshaving non-cylindrical shapes.

While various temperatures, pressures, and/or leach times may enableleaching of a PCD article to a greater degree, such conditions mayundesirably cause passage of a leaching solution between the PCD articleand a shielding cup surrounding the PCD article, increasing contactbetween the leaching solution and a substrate or other protected part ofthe PCD article. Various temperatures, pressures, and/or leach times mayalso accelerate the rate at which the leaching solutions attacksubstrate materials, such as carbide materials, resulting in excessivecorrosion and/or damage to the substrates.

SUMMARY

The instant disclosure is directed to exemplary methods of processingpolycrystalline diamond elements. In some examples, a method ofprocessing polycrystalline diamond elements may comprise forming aprotective layer over only a selected portion of a polycrystallinediamond element. The polycrystalline diamond element may comprise apolycrystalline diamond table. The method may also comprise exposing atleast a portion of the polycrystalline diamond element to a leachingsolution such that the leaching solution contacts an exposed surfaceregion of the polycrystalline diamond table and at least a portion ofthe protective layer.

In some embodiments, the polycrystalline diamond element may alsocomprise a substrate bonded to the polycrystalline diamond table. Theselected portion may comprise at least a portion of a surface of thepolycrystalline diamond table and/or at least a portion of a surface ofthe substrate. In some embodiments, an outer layer may be formed on atleast a portion of an outer surface of the protective layer.

The protective layer may be substantially impermeable to the leachingsolution. In some examples, the protective layer may comprise asubstantially inert material. In various embodiments, the protectivelayer may comprise one or more of metal, polymer, glass, carbon, and/orceramic materials. In at least one example, the protective layer maycomprise a metallic material including at least one of a refractorymetal, a precious metal, a steel alloy, and/or a steel derivative alloy.In various examples, the protective layer may comprise a thermoplasticmaterial. In at least one example, the protective layer may comprisegraphite and/or a glass sealant. In various examples, the protectivelayer may comprise a thermosetting material, which may be formed overthe selected portion of the polycrystalline diamond element by curingthe thermosetting material (e.g., by applying heat, pressure, UVradiation, etc.).

In various embodiments, forming the protective layer over only aselected portion of the polycrystalline diamond element may compriseforming an intercalated hybrid layer at an interface between theprotective layer and the polycrystalline diamond element. Theintercalated hybrid layer may comprise portions of the protective layerdisposed between portions of the polycrystalline diamond element. In atleast one embodiment, the intercalated hybrid layer may compriseportions of the protective layer disposed within cavities defined in thepolycrystalline diamond element.

According to at least one embodiment, the protective layer may be formedover the selected portion of the polycrystalline diamond element byexposing the protective layer to an elevated temperature and an elevatedpressure. The elevated temperature may comprise a temperature of about50° C. or higher and the elevated pressure may comprise a pressure ofabout 1000 psi or higher.

In at least one embodiment, the method may comprise chamfering an edgeportion of the polycrystalline diamond table. Chamfering the edgeportion of the polycrystalline diamond table may comprise making areference mark on a portion of the polycrystalline diamond element andgrinding the edge portion of the polycrystalline table with a centerlessgrinder, utilizing the reference mark to locate the edge portion. Invarious embodiments, at least a portion of the protective layer may beremoved from the selected portion of the polycrystalline diamond element(e.g., by lapping, grinding, etc.).

According to some embodiments, a method of processing a polycrystallinediamond element may comprise forming a protective layer and anintermediate layer on a selected portion of a polycrystalline diamondelement. In at least one example, forming the protective layer and theintermediate layer on the selected portion of the polycrystallinediamond element may comprise affixing the intermediate layer to theselected portion of the polycrystalline diamond element and affixing theprotective layer to the intermediate layer.

In some embodiments, a method of processing a polycrystalline diamondelement may comprise surrounding at least a portion of a polycrystallinediamond element with a protective heat-shrink layer, the polycrystallinediamond element comprising a polycrystalline diamond table. The methodmay also comprise exposing the protective heat-shrink material to atemperature at which the heat-shrink material contracts against aselected portion of the polycrystalline diamond element.

Exemplary methods of manufacturing polycrystalline diamond elements arealso disclosed. According to at least one embodiment, a method ofmanufacturing a polycrystalline diamond element may comprise forming aprotective layer over only a selected portion of a polycrystallinediamond element during sintering of a polycrystalline diamond table ofthe polycrystalline diamond element such that an intercalated hybridlayer is formed between the protective layer and the polycrystallinediamond element. The method may also comprise exposing at least aportion of the polycrystalline diamond element to a leaching solutionsuch that the leaching solution contacts an exposed surface region ofthe polycrystalline diamond table and at least a portion of theprotective layer. The protective layer may be substantially impermeableto the leaching solution.

According to at least one example, forming the polycrystalline diamondelement and the protective layer formed over the selected portion of thepolycrystalline diamond element may comprise disposing a particulatemixture comprising diamond particles adjacent to the protective layerand sintering the particulate mixture to form the polycrystallinediamond table such that the protective layer is formed over at least aportion of a surface of the polycrystalline diamond table.

According to various embodiments, forming the polycrystalline diamondelement and the protective layer formed over the selected portion of thepolycrystalline diamond element may further comprise disposing theparticulate mixture comprising diamond particles adjacent to asubstrate. The selected portion of the polycrystalline diamond elementmay comprise at least a portion of a surface of the substrate. In atleast one example, forming the polycrystalline diamond element and theprotective layer over the selected portion of the polycrystallinediamond element may also comprise partially removing a portion of theprotective layer from a portion of a surface of the polycrystallinediamond table.

Features from any of the described embodiments may be used incombination with one another in accordance with the general principlesdescribed herein. These and other embodiments, features, and advantageswill be more fully understood upon reading the following detaileddescription in conjunction with the accompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate a number of exemplary embodimentsand are a part of the specification. Together with the followingdescription, these drawings demonstrate and explain various principlesof the instant disclosure.

FIG. 1 is a perspective view of an exemplary superabrasive elementincluding a substrate and a superabrasive table according to at leastone embodiment.

FIG. 2 is a perspective view of an exemplary superabrasive disccomprising a superabrasive table according to various embodiments.

FIG. 3 is a cross-sectional side view of a portion of a superabrasivetable that is at least partially leached according to at least oneembodiment.

FIG. 4 is a magnified cross-sectional side view of a portion of thesuperabrasive table illustrated in FIG. 3.

FIG. 5A is a perspective view of an exemplary superabrasive element thatis partially surrounded by a protective layer.

FIG. 5B is a cross-sectional side view of the superabrasive element andprotective layer illustrated in FIG. 5A.

FIG. 5C is a cross-sectional side view of an exemplary superabrasiveelement and protective layer according to at least one embodiment.

FIG. 5D is a cross-sectional side view of the superabrasive element andprotective layer illustrated in FIG. 5C following leaching of at least aportion of the superabrasive element.

FIG. 6A is a cross-sectional side view of an exemplary sinteringconfiguration including a substrate and a particulate mixture disposedin a sintering container prior to sintering according to at least oneembodiment.

FIG. 6B is a cross-sectional side view of the sintering configurationillustrated in FIG. 6A following sintering.

FIG. 6C is a cross-sectional side view of the sintering configurationillustrated in FIG. 6B after a portion of the sintering container hasbeen removed.

FIG. 7A is a cross-sectional side view of a portion of a protectivelayer formed over a selected portion an exemplary superabrasive elementaccording to at least one embodiment.

FIG. 7B is a magnified cross-sectional side view of a portion of theexemplary superabrasive element and the protective layer illustrated inFIG. 7A.

FIG. 8A is a top view of a superabrasive face of an exemplarysuperabrasive element and a patterned protective layer formed over aselected portion of the superabrasive face according to at least oneembodiment.

FIG. 8B is a top view of a superabrasive face of an exemplarysuperabrasive element and a protective layer formed over a selectedportion of the superabrasive face according to at least one embodiment.

FIG. 8C is a top view of a superabrasive face of an exemplarysuperabrasive element and a protective layer formed over a selectedportion of the superabrasive face according to at least one embodiment.

FIG. 9A is a perspective view of an exemplary superabrasive element thatis partially surrounded by a protective layer.

FIG. 9B is a perspective view of an exemplary superabrasive element thatis partially surrounded by a protective layer.

FIG. 10A is a cross-sectional side view of an exemplary superabrasiveelement that is partially surrounded by a protective layer and anintermediate layer according to at least one embodiment.

FIG. 10B is a cross-sectional side view of an exemplary superabrasiveelement that is partially surrounded by a protective layer and an outerlayer according to at least one embodiment.

FIG. 11A is a cross-sectional side view of an exemplary sinteringconfiguration including a substrate and a particulate mixture disposedin a sintering container prior to sintering according to at least oneembodiment.

FIG. 11B is a cross-sectional side view of the sintering configurationillustrated in FIG. 11A following sintering and leaching.

FIG. 11C is a cross-sectional side view of the sintering configurationillustrated in FIG. 11B after a portion of the sintering container hasbeen removed.

FIG. 12 is a perspective view of an exemplary superabrasive element anda heat-shrink layer according to at least one embodiment.

FIG. 13A is a cross-sectional side view of the superabrasive elementillustrated in FIG. 11 partially surrounded by the heat-shrink layer.

FIG. 13B is a cross-sectional side view of the superabrasive elementillustrated in FIG. 11 partially encased by the heat-shrink layer.

FIG. 14 is a perspective view of an exemplary drill bit according to atleast one embodiment.

FIG. 15 is a top view of the exemplary drill bit illustrated in FIG. 14.

FIG. 16 is a partial cut-away perspective view of an exemplary thrustbearing apparatus according to at least one embodiment.

FIG. 17 is a partial cut-away perspective view of an exemplary radialbearing apparatus according to at least one embodiment.

FIG. 18 is a partial cut-away perspective view of an exemplarysubterranean drilling system according to at least one embodiment.

FIG. 19 is a flow diagram of an exemplary method of processing apolycrystalline diamond element according to at least one embodiment.

FIG. 20 is a flow diagram of an exemplary method of manufacturing apolycrystalline diamond element according to at least one embodiment.

FIG. 21 is a flow diagram of an exemplary method of processing apolycrystalline diamond element according to at least one embodiment.

FIG. 22 is a flow diagram of an exemplary method of processing apolycrystalline diamond element according to at least one embodiment.

Throughout the drawings, identical reference characters and descriptionsindicate similar, but not necessarily identical, elements. While theexemplary embodiments described herein are susceptible to variousmodifications and alternative forms, specific embodiments have beenshown by way of example in the drawings and will be described in detailherein. However, the exemplary embodiments described herein are notintended to be limited to the particular forms disclosed. Rather, theinstant disclosure covers all modifications, equivalents, andalternatives falling within the scope of the appended claims.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The instant disclosure is directed to superabrasive cutting elements anddrill bits used in drilling and/or other cutting operations. The cuttingelements may be optimized for cutting selected formations. The optimizedcutting elements may also have optimal strength and thermal stabilitycharacteristics suited to selected formation types. The cutting elementsdisclosed herein may be used in a variety of applications, such asdrilling tools, machining equipment, cutting tools, and otherapparatuses, without limitation. The instant disclosure is also directedto methods for manufacturing superabrasive cutting elements optimizedfor cutting selected formations.

As used herein, the terms “superabrasive” and “superhard” may refer tomaterials exhibiting a hardness exceeding a hardness of tungstencarbide. For example, a superabrasive article may represent an articleof manufacture, at least a portion of which may exhibit a hardnessexceeding the hardness of tungsten carbide. As used herein, the term“cutting” may refer broadly to machining processes, drilling processes,boring processes, and/or any other material removal process utilizing acutting element.

FIG. 1 is a perspective view of an exemplary superabrasive element 10according to at least one embodiment. As illustrated in FIG. 1,superabrasive element 10 may comprise a superabrasive table 14 affixedto or formed upon a substrate 12. Superabrasive table 14 may be affixedto substrate 12 at interface 26. Superabrasive element 10 may comprise arear face 18 and a substrate side surface 16 formed by substrate 12.Superabrasive element 10 may also comprise a superabrasive face 20, asuperabrasive side surface 22, and a superabrasive edge 24 formed bysuperabrasive table 14. Superabrasive edge 24 may comprise an angularand/or rounded edge formed at the intersection of superabrasive sidesurface 22 and superabrasive face 20. In various embodiments,superabrasive edge 24 may comprise a chamfered surface or other selectedgeometry (e.g., one or more radius and/or one or more chamfer, etc.)extending between superabrasive side surface 22 and superabrasive face20. In some embodiments, superabrasive edge 24 may act as a cutting edgeduring drilling and/or cutting operations.

Substrate 12 may comprise any suitable material on which superabrasivetable 14 may be formed. In at least one embodiment, substrate 12 maycomprise a cemented carbide material, such as a cobalt-cemented tungstencarbide material and/or any other suitable material. Further, substrate12 may include a suitable metal-solvent catalyst material, such as, forexample, cobalt, nickel, iron, and/or alloys thereof. Substrate 12 mayalso include any other suitable material including, without limitation,cemented carbides such as titanium carbide, niobium carbide, tantalumcarbide, vanadium carbide, chromium carbide, and/or combinations of anyof the preceding carbides cemented with iron, nickel, cobalt, and/oralloys thereof.

Superabrasive table 14 may be formed of any suitable superabrasiveand/or superhard material or combination of materials, including, forexample PCD. According to additional embodiments, superabrasive table 14may comprise cubic boron nitride, silicon carbide, diamond, and/ormixtures or composites including one or more of the foregoing materials.

Superabrasive table 14 may be formed using any suitable technique. Forexample, superabrasive table 14 may comprise a PCD layer formed bysubjecting a plurality of diamond particles (e.g., diamond particleshaving an average particle size between approximately 0.5 μm andapproximately 150 μm) to a HPHT sintering process in the presence of ametal-solvent catalyst, such as cobalt, nickel, iron, and/or any othersuitable group VIII element or alloys thereof. During a HPHT sinteringprocess, adjacent diamond crystals in a mass of diamond particles maybecome bonded to one another, forming a PCD table comprising bondeddiamond crystals. In at least one example, bonded diamond crystals insuperabrasive table 14 may have an average grain size of approximately20 μm or less. Further, during a HPHT sintering process, diamond grainsmay become bonded to an adjacent substrate 12 at interface 26.

According to various embodiments, superabrasive table 14 may be formedby placing diamond particles adjacent to a substrate 12 comprisingcobalt-cemented tungsten carbide. The resulting sintered PCD layer mayinclude various interstitial materials, including, for example, cobalt,tungsten, and/or tungsten carbide. In some examples, material componentsof substrate 12 may migrate into a mass of diamond particles used toform superabrasive table 14 during HPHT sintering.

According to at least one embodiment, as the mass of diamond particlesis sintered, a metal-solvent catalyst may melt and flow from substrate12 into the mass of diamond particles. As the metal-solvent flows intosuperabrasive table 14, it may also dissolve and/or carry additionalmaterials, such as tungsten and/or tungsten carbide, from substrate 12into the mass of diamond particles. As the metal-solvent catalyst flowsinto the mass of diamond particles, the metal-solvent catalyst, and anydissolved and/or undissolved materials, may at least partially fillspaces between the diamond particles. The metal-solvent catalyst mayfacilitate bonding of adjacent diamond particles to form a PCD layer.Additionally, as the PCD layer is cooled, the metal-solvent may solidifyand adhere to diamond grains in the PCD layer, thereby holding the PCDlayer in a compressed state.

FIG. 2 is a perspective view of an exemplary superabrasive disc 28according to at least one embodiment. As illustrated in FIG. 2,superabrasive disc 28 may comprise a superabrasive table 14 that is notattached to a substrate. Superabrasive disc 28 may be formed using anysuitable technique, including, for example, HPHT sintering, as describedabove. In some examples, superabrasive disc 28 may be manufactured byfirst forming a superabrasive element comprising a superabrasive layerbonded to a substrate (e.g., superabrasive element 10 illustrated inFIG. 1). Superabrasive table 14 may be separated from substrate 12 toform superabrasive disc 28. Superabrasive table 14 may be separated fromsubstrate 12 using a lapping process, a grinding process, awire-electrical-discharge machining (“wire EDM”) process, or any othersuitable material-removal process, without limitation. Superabrasivedisc 28 may comprise a rear face 19 that is formed by superabrasivetable 14.

FIG. 3 is a cross-sectional side view of a portion of an exemplarysuperabrasive table 14, such as exemplary superabrasive tables 14illustrated in FIGS. 1 and 2. Superabrasive table 14 may comprise acomposite superhard material, such as a PCD material. A PCD material mayinclude a matrix of bonded diamond grains and interstitial regionsdefined between the bonded diamond grains. Such interstitial regions maybe at least partially filled with various materials. In someembodiments, a metal-solvent catalyst may be disposed in interstitialregions in superabrasive table 14. Tungsten, tungsten carbide, and/orother materials may also be present in the interstitial regions.

Following sintering, various materials, such as a metal-solventcatalyst, remaining in interstitial regions within superabrasive table14 may reduce the thermal stability of superabrasive table 14 atelevated temperatures. In some examples, differences in thermalexpansion coefficients between diamond grains in superabrasive table 14and a metal-solvent catalyst in interstitial regions between the diamondgrains may weaken portions of superabrasive table 14 that are exposed toelevated temperatures, such as temperatures developed during drillingand/or cutting operations. The weakened portions of superabrasive table14 may be excessively worn and/or damaged during the drilling and/orcutting operations.

Removing the metal-solvent catalyst and/or other materials fromsuperabrasive table 14 may improve the heat resistance and/or thermalstability of superabrasive table 14, particularly in situations wherethe PCD material may be exposed to elevated temperatures. Themetal-solvent catalyst and/or other materials may be removed fromsuperabrasive table 14 using any suitable technique, including, forexample, leaching. In at least one embodiment, a metal-solvent catalyst,such as cobalt, may be removed from regions of superabrasive table 14that may experience elevated temperatures, such as regions adjacent tothe working surfaces of superabrasive table 14. Removing a metal-solventcatalyst from superabrasive table 14 may prevent damage to the PCDmaterial caused by expansion of the metal-solvent catalyst.

At least a portion of a metal-solvent catalyst, such as cobalt, as wellas other materials, may be removed from at least a portion ofsuperabrasive table 14 using any suitable technique, without limitation.For example, chemical and/or gaseous leaching may be used to remove ametal-solvent catalyst from superabrasive table 14 up to a depth D froma surface of superabrasive table 14, as illustrated in FIG. 3. As shownin FIG. 3, depth D may be measured relative to an external surface ofsuperabrasive table 14, such as superabrasive face 20, superabrasiveside surface 22, and/or superabrasive edge 24. Any suitable leachingsolution and/or gas mixture may be used to leach materials fromsuperabrasive table 14, without limitation. In some embodiments, onlyportions of one or more surfaces of superabrasive table 14 may beleached, leaving remaining portions of the surfaces unleached. Othersuitable techniques may be used for removing a metal-solvent catalystand/or other materials from superabrasive table 14 or may be used toaccelerate a chemical leaching process. For example, exposing thesuperabrasive material to electric current, microwave radiation, and/orultrasound may be employed to leach or to accelerate a chemical leachingprocess, without limitation.

Following leaching, superabrasive table 14 may comprise a first volume35 that is substantially free of a metal-solvent catalyst, as shown inFIG. 3. However, small amounts of metal-solvent catalyst may remainwithin interstices that are inaccessible to the leaching process. Firstvolume 35 may extend from one or more surfaces of superabrasive table 14(e.g., superabrasive face 20, superabrasive side surface 22, and/orsuperabrasive edge 24) to a depth D from the one or more surfaces. Firstvolume 35 may be located adjacent one or more surfaces of superabrasivetable 14.

Following leaching, superabrasive table 14 may also comprise a secondvolume 36 that contains a metal-solvent catalyst, as shown in FIG. 3. Anamount of metal-solvent catalyst in second volume 36 may besubstantially the same prior to and following leaching. In variousembodiments, second volume 36 may be remote from one or more exposedsurfaces of superabrasive table 14. In various embodiments, an amount ofmetal-solvent catalyst in first volume 35 and/or second volume 36 mayvary at different depths in superabrasive table 14. Superabrasive table14 may also include a transition region 37 (depicted as a line forclarity) between first volume 35 and second volume 36. Transition region37 may include amounts of metal-solvent catalyst varying between anamount of metal-solvent catalyst in first volume 35 and an amount ofmetal-solvent catalyst in second volume 36. Transition region 37 maycomprise a relatively narrow region or a relatively thicker regionextending between first volume 35 and second volume 36.

FIG. 4 is a magnified cross-sectional side view of a portion of thesuperabrasive table 14 illustrated in FIG. 3. As shown in FIG. 4,superabrasive table 14 may comprise grains 38 and interstitial regions39 between grains 38 defined by grain surfaces 40. Grains 38 maycomprise grains formed of any suitable superabrasive material,including, for example, diamond grains. At least some of grains 38 maybe bonded to one or more adjacent grains 38, forming a polycrystallinediamond matrix.

Interstitial material 41 may be disposed in at least some ofinterstitial regions 39. Interstitial material 41 may comprise anysuitable material, including, for example, a metal-solvent catalyst. Asshown in FIG. 4, at least some of interstitial regions 39 may besubstantially free of interstitial material 41. At least a portion ofinterstitial material 41 may be removed from at least some ofinterstitial regions 39 during a leaching procedure. For example, asubstantial portion of interstitial material 41 may be removed fromfirst volume 35 during a leaching procedure. Additionally, interstitialmaterial 41 may remain in a second volume 36 following a leachingprocedure.

FIGS. 5A-5D are perspective and cross-sectional side views of exemplarysuperabrasive elements 10 that are at least partially surrounded by aprotective layer 30 according to various embodiments. As shown in FIGS.5A and 5B, protective layer 30 may be formed over at least a portion ofsuperabrasive element 10, including substrate 12. According to variousembodiments, a protective layer may also be formed over at least aportion of a superabrasive disc (e.g., superabrasive disc 28 illustratedin FIG. 2). Protective layer 30 may prevent damage to superabrasiveelement 10 when superabrasive element 10 is exposed to various reactiveagents. For example, protective layer 30 may prevent a leaching solutionfrom chemically damaging certain portions of superabrasive element 10,such as portions of substrate 12, portions of superabrasive table 14, orboth, during leaching.

In various examples, protective layer 30 may comprise one or morematerials that are substantially inert and/or otherwise resistant toacids, bases, and/or other reactive compounds present in a leachingsolution used to leach superabrasive element 10. In some embodiments,protective layer 30 may comprise one or more materials exhibitingsignificant stability at various temperatures and/or pressures,including elevated temperatures and/or pressures used in sintering,leaching, and/or otherwise processing superabrasive element 10.According to various embodiments, protective layer 30 may comprise anysuitable material, including metals, alloys, polymers, carbonallotropes, oxides, carbides, glass materials, ceramics, composites,and/or any combination of the foregoing, without limitation.

In some embodiments, protective layer 30 may comprise one or moremetallic compounds and/or alloys. Suitable metallic compounds mayinclude, without limitation, refractory metals, precious metals, and/orplatinum group metals such as gold and/or platinum. In various examples,protective layer 30 may comprise metal alloys including, withoutlimitation, steel and/or steel derivative alloys such as INCONEL(Special Metals Corporation, Huntington, W. Va.) superalloys.

In various embodiments, protective layer 30 may comprise one or morerefractory materials exhibiting significant chemical stability and/orstrength under a wide range of conditions, including elevatedtemperature and/or pressure conditions. According to at least oneembodiment, suitable refractory materials may include refractory metalssuch as, for example, niobium, tantalum, molybdenum, tungsten, rhenium,chromium, vanadium, hafnium, and/or zirconium. According to someexamples, suitable refractory materials may include various oxides,carbides, carbon allotropes, composites, and/or combinations of theforegoing.

In various embodiments, protective layer 30 may include one or morepolymeric materials, without limitation. For example, protective layer30 may comprise one or more thermoplastic polymer materials, including,without limitation, polyolefin, fluoropolymer, polyvinyl chloride(“PVC”), neoprene, silicone elastomer, and/or synthetic rubbermaterials. Suitable fluoropolymers may include, for example,polytetrafluoroethylene (“PTFE”), fluorinated ethylene propylene, and/orpolyvinylidene difluoride (“PVDF”). In some embodiments, protectivelayer 30 may comprise a heat-shrink material configured to contractagainst a selected portion of superabrasive element 10 followingexposure to heat and/or pressure, as described in greater detail belowwith reference to FIGS. 11-13.

In additional embodiments, protective layer 30 may comprise athermosetting and/or thermoplastic material that may be cured and/oraffixed to superabrasive element 10 through the application of, forexample, heat, pressure, and/or UV radiation. Suitable thermosettingmaterials may include, for example, phenolic, epoxy, polyimide,silicone, and/or various other polymeric thermosetting materials.Examples of suitable thermosetting materials may include, withoutlimitation, EPOMET (Buehler, Ltd., Lake Bluff, Ill.) epoxy resins,KONDUCTOMET (Buehler, Ltd., Lake Bluff, Ill.) phenolic resins, and/orBAKELITE phenolic resins.

In some embodiments, protective layer 30 may include one or more formsof carbon, including, for example, graphite, diamond, amorphous carbon,and/or other suitable carbon allotropes. In at least one embodiment,protective layer 30 may comprise ceramic and/or glass materials. Forexample, protective layer 30 may comprise a coating and/or sealantcomposition including one or more ceramic and/or glass compounds.Suitable glass materials may include, for example, AREMCO-SEAL (AremcoProducts, Inc., Valley Cottage, N.Y.) high-temperature glass sealants.In some embodiments, protective layer 30 may primarily comprise carbon,ceramic, and/or glass materials. In various embodiments, carbon,ceramic, and/or glass materials may be combined with and/or dispersedthroughout other materials in protective layer 30. For example, carbon,ceramic, and/or glass particles and/or fibers may be dispersedthroughout a polymeric-based material.

Protective layer 30 may comprise a material that is configured to bedirectly and/or indirectly formed over at least a portion ofsuperabrasive element 10. For example, at least a portion of protectivelayer 30 may be affixed to surface portions of substrate 12 and/orsuperabrasive table 14 such that a leaching solution is prevented orinhibited from passing between protective layer 30 and superabrasiveelement 10. Protective layer 30 may be formed over at least a portion ofsubstrate 12 and/or superabrasive table 14 of superabrasive element 10through any suitable mechanism, without limitation. In at least oneexample, protective layer 30 may be bonded to an exterior portion ofsuperabrasive element 10 through ionic bonds, covalent bonds, and/orvarious intermolecular bonds. In some examples, protective layer 30 maybe affixed to superabrasive element 10 through mechanical and/orfrictional attachment of protective layer 30 to superabrasive element10. Protective layer 30 may also be affixed to at least a portion ofsubstrate 12 and/or superabrasive table 14 of superabrasive element 10through interference fitting.

In some embodiments, protective layer 30 may comprise a solid layer thatis formed over superabrasive element 10. For example, protective layer30 may be fused to superabrasive table 14 and/or substrate 12 byapplying elevated heat and/or pressure to protective layer 30 and/orsuperabrasive element 10. In at least one example, protective layer 30may comprise a solid member (e.g., a solid container or cup) that isplaced adjacent to a particulate mixture (e.g., particulate mixture 32illustrated in FIG. 6A) and/or substrate 12 prior to formingsuperabrasive table 14. Subsequently, elevated temperature and pressuremay be applied to protective layer 30, the particulate mixture, andsubstrate 12, thereby sintering the particulate mixture to formsuperabrasive table 14 and affixing protective layer 30 to superabrasivetable 14 and/or substrate 12.

In various embodiments, protective layer 30 may be placed adjacent to asuperabrasive element 10 that comprises a previously sinteredsuperabrasive table 14. Elevated temperature and/or pressure may then beapplied to protective layer 30 and/or superabrasive element 10, therebyfusing protective layer 30 to at least a portion of superabrasiveelement 10. Suitable techniques utilizing elevated heat and/or pressureto affix protective layer 30 to superabrasive element 10 may include,without limitation, heating and pressurizing protective layer 30 in ahigh-temperature/high-pressure oven, heating and pressurizing protectivelayer 30 in a mounting press, heating protective layer 30 in a vacuumoven, swaging protective layer 30, crimping protective layer 30, and/orheat-shrinking protective layer 30.

In some embodiments, a combination of elevated heat and/or pressure maycause portions of protective layer 30 to at least partially conform toprojections, cavities, indentations, and/or other surface irregularitiesdefined by and/or adjacent to a surface portion of superabrasive element10. By at least partially conforming to surface irregularities formedand/or defined by superabrasive element 10, protective layer 30 may bemechanically affixed to at least a portion of substrate 12 and/orsuperabrasive table 14.

In some embodiments, a thermosetting material, such as a thermosettingresin, may be disposed adjacent a surface portion of superabrasiveelement 10 and cured to form protective layer 30 through the applicationof heat and/or pressure. In various embodiments, a material used to formprotective layer 30, such as a metallic composition and/or thermoplasticresin, may be heated to a temperature above the melting point of thematerial and applied to a surface portion of superabrasive element 10.The melted composition may then be solidified to form protective layer30 by cooling the composition below the melting point.

According to some embodiments, a material used to form protective layer30 may be applied to an exterior of superabrasive element 10 as asolution and/or as an uncured or semi-cured composition. Such materialsmay then be solidified to form protective layer 30 using any suitabletechnique. For example, solvent components may be evaporated from asolution to form protective layer 30. In various examples, a materialmay be cured to form protective layer 30 by exposing the material to anappropriate amount of temperature, pressure, and/or radiation. Forexample, materials may be cured to form superabrasive 30 by, forexample, exposing the materials to heat, ultraviolet radiation,microwave radiation, ultrasonic energy, and/or a curing agent. In oneexample, protective layer 30 may comprise a photopolymer.

According to some embodiments, protective layer 30 may be formed oversuperabrasive element 10 by disposing an intermediate material betweenat least a portion of protective layer 30 and superabrasive element 10(e.g., intermediate layer 42 illustrated in FIG. 9). For example, anadhesive compound may be disposed between protective layer 30 andsuperabrasive element 10, affixing protective layer 30 to superabrasiveelement 10. According to some embodiments, a layer of thermoplasticadhesive may be disposed on an inside portion of protective layer 30adjacent to superabrasive element 10. In at least one example, anintermediate layer may be affixed to at least a portion of superabrasiveelement 10 and to at least a portion of protective layer 30.

In one example, protective layer 30 may comprise an adhesive tape. Insome examples, a solvent may be applied to protective layer 30, at leastpartially dissolving a portion of protective layer 30. The at leastpartially dissolved portion of protective layer 30 may be placed incontact with superabrasive element 10. Subsequently, the solvent may beevaporated and the at least partially dissolved portion of protectivelayer 30 may solidify and adhere to superabrasive element 10.

Protective layer 30 may be selectively formed over or applied toportions of substrate 12 and/or superabrasive table 14 in any pattern,design, or as otherwise desired, without limitation. According to someembodiments, protective layer 30 may be formed over a selected portionof superabrasive element 10 such that an exposed surface region ofsuperabrasive element 10 is exposed. For example, protective layer 30may be affixed to a selected portion of superabrasive element 10 thatincludes at least a portion of substrate 12 and/or superabrasive table14.

As illustrated in FIG. 5B, protective layer 30 may be formed over aselected portion of superabrasive element 10 that includes rear face 18and substrate side surface 16 of substrate 12, thereby inhibiting orpreventing undesired corrosion of substrate 12 during leaching. Asfurther shown in FIG. 5B, the selected portion may also include aportion of superabrasive side surface 22 of superabrasive table 14,further inhibiting or preventing a leaching solution from contactingsubstrate 12 and/or a portion of superabrasive table 14 adjacent tosubstrate 12. An exposed surface region of superabrasive element 10 thatis not covered by protective layer 30 may include portions ofsuperabrasive table 14, including at least a portion of superabrasiveside surface 22 and superabrasive face 20, as illustrated in FIGS. 5Aand 5B.

According to some embodiments, protective layer 30 may be formed oversuperabrasive table 14 such that protective layer 30 is not formed onportions of superabrasive table 14 that are configured to be used ascutting surfaces and/or cutting edges (e.g., cutting surface and/orcutting edges of a cutting element). In at least one embodiment,protective layer 30 may be formed on or applied to superabrasive table14 in an alternating pattern such that alternating leached and unleachedregions may be formed on superabrasive table 14. Forming protectivelayer 30 over superabrasive element 10 in such configurations may enableselective optimization of various characteristics of superabrasiveelement 10 through selective leaching of superabrasive table 14.

During leaching, a region of superabrasive element 10 that is notcovered by protective layer 30 (i.e., an exposed surface region) may beexposed to a leaching solution during leaching. Additionally, theleaching solution may be inhibited or prevented from contacting a regionwhich is covered by protective layer 30. Accordingly, the leachingsolution may be inhibited or prevented from dissolving and/or corrodingportions of superabrasive element 10 at and/or adjacent to a selectedportion on which protective layer 30 is formed. The leaching solutionmay also be inhibited or prevented from migrating between superabrasiveelement 10 and protective layer 30, further protecting portions ofsuperabrasive element 10 at and/or adjacent to the selected portion.

According to various embodiments, edges of protective layer 30 may besecurely affixed to superabrasive element 10, thereby preventing theedges from separating from superabrasive element 10 under variousconditions, such as conditions existing during leaching and/or HPHTsintering. The edges of protective layer 30 may clearly define one ormore regions of superabrasive element 10 to be leached, such as anexposed surface region, while preventing leaching of selected regions ofsuperabrasive element 10, such as a selected portion on which protectivelayer 30 is formed.

In order to securely fix edges of protective layer 30 to superabrasiveelement 10, protective layer 30 may comprise a material that is capableof strongly affixing to superabrasive table 14 and/or substrate 12 undervarious conditions. In some embodiments, protective layer 30 may alsocomprise a material that is capable of substantially maintaining itsshape and/or configuration during sintering and/or leaching ofsuperabrasive element 10. For example, protective layer 30 may comprisea material that is substantially resistant to various compounds presentin a leaching solution. Protective layer 30 may also comprise a materialthat is substantially resistant to expansion and/or shrinkage underconditions present during sintering and/or leaching of superabrasiveelement 10. Such materials may include one or more of theabove-described materials suitable for use in protective layer 30,without limitation.

Superabrasive element 10 may comprise any suitable shape, including,without limitation, a symmetrical or a non-symmetrical shape. In atleast one embodiment, as illustrated in FIGS. 5A and 5B, superabrasiveelement 10 may comprise a generally cylindrical element centered about acentral axis 27. A location where central axis 27 intersectssuperabrasive face 20 may be represented by central location 29.

In various embodiments, as illustrated in FIGS. 5A and 5B, asuperabrasive edge 24 (e.g., a chamfered cutting edge) extending betweensuperabrasive side surface 22 and superabrasive face 20 may be formed onsuperabrasive table 14. Superabrasive edge 24 may be formed prior to orfollowing sintering of superabrasive element 10. In a case wheresuperabrasive edge 24 is formed following sintering of superabrasiveelement 10, protective layer 30 may be removed from superabrasiveelement 10 prior to formation of superabrasive edge 24 using anysuitable technique, including, for example, lapping and/or grinding.

Protective layer 30 may be removed from superabrasive element 10 suchthat outer surfaces of superabrasive element 10, including substrateside surface 16 and/or superabrasive side surface 22, are substantiallycentered about central axis 27. Superabrasive element 10 may then beplaced on a collet or other holding member sized to fit around andsecurely hold an outer surface of superabrasive element 10, such assubstrate side surface 16. Such a collet or holding member may securesuperabrasive element 10 to a grinding machine. The grinding machine(e.g., an outer diameter or OD grinder) may then rotate the collet,causing superabrasive element 10 to rotate about central axis 27. Assuperabrasive element 10 rotates, a grinding surface, such as anabrasive surface suited for removing material from superabrasive table14, may grind an edge portion of superabrasive table 14 until a desiredsuperabrasive edge 24 is obtained.

In a case where superabrasive edge 24 is formed prior to leaching ofsuperabrasive element 10, protective layer 30 may remain on at least aportion of superabrasive element 10 during formation of superabrasiveedge 24. For example, as illustrated in FIG. 5B, protective layer 30 maysurround outer portions of superabrasive element 10, such as substrateside surface 16 and/or superabrasive side surface 22. In some examples,protective layer 30 may have an uneven outer profile that is notcentered about central axis 27.

In various embodiments, using a collet and an OD grinding machine toprocess a superabrasive element 10 having an uneven outer profiledefined by protective layer 30 may result in the formation of arelatively nonuniform and/or uneven superabrasive edge 24. In order toform a desired edge geometry (e.g., a relatively uniform superabrasiveedge 24) on a superabrasive element 10 surrounded by an unevenprotective layer 30, a reference mark may be formed on superabrasiveelement 10 at any suitable location, such as a central location onsuperabrasive table 14. For example, a reference mark may be made onsuperabrasive face 20 at and/or near central location 29. A referencemark may also be placed on any other suitable portion of superabrasiveelement 10, without limitation. A reference mark formed on superabrasiveelement 10 may include an ink or painted coating applied tosuperabrasive element 10, an indentation and/or notch formed insuperabrasive element 10, and/or any other suitable type of mark orlocation indicator, without limitation.

A computer numerical control (“CNC”) grinding machine, such as acenterless CNC grinding machine, may utilize the reference mark as aguide to form a relatively even superabrasive edge 24 on superabrasivetable 14. For example, a CNC grinding machine may be programmed to lockonto the reference mark using one or more sensors while superabrasivetable 14 is being ground to form superabrasive edge 24. In someexamples, a CNC grinding machine may be programmed to utilize thereference mark as an indicator of the location of central axis 27 and/orthe location of an outer surface of superabrasive element 10, enablingsuperabrasive edge 24 to be formed as desired (e.g., in a relativelyuniform manner about central axis 27), regardless of variations inprotective layer 30 and/or variations in outer surface portions ofsuperabrasive element 10.

In at least one example, a CNC grinding machine may also be used to formedges on non-cylindrical and/or asymmetrical elements. For example, oneor more reference marks may be made on a non-cylindrical and/orasymmetrical superabrasive element to indicate various points ofreference that may be utilized by a CNC grinding machine to form anydesired edge geometry, such as relatively evenly chamfered edges.

FIGS. 5C and 5D are cross-sectional side views of an exemplarysuperabrasive element 10 that is at least partially surrounded byprotective layer 30 according to various embodiments. As illustrated inFIG. 5C, protective layer 30 may substantially cover superabrasive sidesurface 22 up to superabrasive edge 24. When superabrasive element 10 isexposed to a leaching solution, the leaching solution may contactsuperabrasive face 20 and superabrasive edge 24 and portions ofsuperabrasive table 14 adjacent to superabrasive face 20 andsuperabrasive edge 24 may be leached by the solution. Protective layer30 may substantially prevent a leaching solution from contactingsuperabrasive side surface 22. Accordingly, as illustrated in FIG. 5D, aleached volume, or first volume 35 (e.g., first volume 35 in FIG. 3),may be located adjacent to superabrasive face 20 and superabrasive edge24 following leaching. In at least one example, at least a portion ofsuperabrasive table 14 and protective layer 30 may be removed throughgrinding to form superabrasive edge 24, as illustrated in FIGS. 5C and5D.

FIGS. 6A-6C illustrate an exemplary sintering configuration for forminga superabrasive element 10 and forming a protective layer 30 oversuperabrasive element 10 according to at least one embodiment. Asillustrated in FIGS. 6A-6C, protective layer 30 may be formed from asintering container used in sintering superabrasive element 10.Protective layer 30 may be fused to superabrasive element 10 duringsintering of superabrasive table 14.

FIG. 6A is a cross-sectional side view of an exemplary sinteringconfiguration for forming a superabrasive element. As illustrated inthis figure, substrate 12 may be disposed adjacent to a particulatemixture 32, and substrate 12 and particulate mixture 32 may besurrounded by protective layer 30. In at least one embodiment,protective layer 30 may comprise a sintering container or cartridgeconfigured to surround and hold substrate 12 and particulate mixture 32during sintering. Particulate mixture 32 may comprise a mixture ofsuperhard particles, such as, for example, diamond particles. In someembodiments, particulate mixture 32 may also comprise a metal-solventcatalyst dispersed with diamond particles. For example, particulatemixture 32 may comprise particles of cobalt intermixed with diamondparticles. In some embodiments, substrate 12 may comprise ametal-solvent catalyst that flows into particulate mixture 32 duringsintering. For example, substrate 12 may comprise a cobalt-cementedtungsten carbide material.

In some examples, as illustrated in FIG. 6A, substrate 12 may be loadedinto the sintering container such that substrate 12 contacts a rearsurface of the sintering container. Particulate mixture 32 may then beloaded into the sintering container adjacent substrate 12 and a cover 34may be placed at a front end of the sintering container adjacentparticulate mixture 32. Accordingly, protective layer 30 and cover 34may form a sintering container encasing substrate 12 and particulatemixture 32. In some examples, particulate mixture 32 may be loaded intothe sintering container first, followed by substrate 12. Cover 34 maythen be placed adjacent substrate 12.

Protective layer 30 and/or cover 34 may comprise any material orcombination of materials suitable for encasing substrate 12 andparticulate mixture 32 during sintering. For example, protective layer30 and/or cover 34 may comprise a material or combination of materialscapable of withstanding high temperatures and/or pressures during HPHTsintering. For example, protective layer 30 and/or cover 34 may compriseone or more refractory metals, including, for example, niobium,tantalum, molybdenum, tungsten, rhenium, chromium, vanadium, hafnium,and/or zirconium. Protective layer 30 and/or cover 34 may also compriseany other metallic and/or nonmetallic material suitable for encasingsubstrate 12 and/or particulate mixture 32 during sintering.

FIG. 6B is a cross-sectional side view of the exemplary sinteringconfiguration illustrated in FIG. 6A following sintering of particulatemixture 32 to form superabrasive table 14. During HPHT sintering,substrate 12, particulate mixture 32, protective layer 30, and/or cover34 may be subjected to ultra-high temperatures and pressures. Underthese HPHT sintering conditions, adjacent superhard particles, such asdiamond particles, may become bonded to each other to form superabrasivetable 14 comprising a superhard and/or superabrasive material, such as,for example, a polycrystalline diamond material comprising a network ofsuperhard grains (e.g., grains 38 illustrated in FIG. 4).

During the HPHT sintering process, superhard grains adjacent tosubstrate 12 may become bonded to substrate 12 at interface 26. In atleast one embodiment, a metallic compound, such as a metal-solventcatalyst, may be melted during HPHT sintering and may be disposedbetween interstitial spaces and/or cavities in superabrasive table 14and/or substrate 12. Following HPHT sintering, the metallic compound maybe cooled and hardened, securely bonding superabrasive table 14 tosubstrate 12 at interface 26.

According to at least one embodiment, following HPHT sintering, at leasta portion of protective layer 30 may be bonded and/or otherwise affixedto superabrasive table 14 and/or substrate 12 at an interface 31extending between protective layer 30 and table 14 and/or betweenprotective layer 30 and substrate 12 (e.g., interface 31 illustrated inFIGS. 7A and 7B). In some embodiments, a combination of elevated heatand/or pressure may cause portions of protective layer 30 to at leastpartially conform to projections, cavities, indentations, and/or othersurface irregularities defined by and/or adjacent to a surface portionof superabrasive element 10, such as a surface portion of substrate 12and/or superabrasive table 14. By at least partially conforming tosurface irregularities defined by superabrasive element 10, protectivelayer 30 may be affixed to at least a portion of substrate 12 and/orsuperabrasive table 14.

In some examples, cover 34 may also be affixed to at least a portion ofsuperabrasive table 14 and/or substrate 12 following sintering. Cover 34and/or protective layer 30 may be removed from at least a portion ofsuperabrasive table. For example, as illustrated in FIG. 6B, cover 34and a portion of protective layer 30 may be removed from a portion ofsuperabrasive table 14 using any suitable technique, such as, forexample, lapping or grinding.

FIG. 6C is a cross-sectional side view of the exemplary sinteringconfiguration illustrated in FIGS. 6A and 6B after a portion ofprotective layer 30 has been removed from at least a portion ofsuperabrasive element 10. As illustrated in FIG. 6C, a portion ofprotective layer 30 may be selectively removed from a portion ofsuperabrasive side surface 22 of superabrasive table 14. According tovarious embodiments, protective layer 30 may be removed from a portionof superabrasive element 10 such that protective layer 30 is affixed toa selected portion of superabrasive element 10 and such that an exposedsurface region of superabrasive element 10 is exposed. For example, asillustrated in FIG. 6C, protective layer 30 may be selectively removedfrom at least a portion of superabrasive table 14, thereby exposing anexposed surface region of superabrasive element 10 that includes atleast a portion of superabrasive side surface 22 and/or superabrasiveface 20.

Following removal of a portion of protective layer 30 from superabrasiveelement 10, protective layer 30 may remain affixed to a selected portionof superabrasive element 10. In at least one example, protective layer30 may remain affixed to a selected portion of superabrasive element 10that includes at least a portion of substrate 12 and/or superabrasivetable 14. In some examples, as illustrated in FIG. 6C, protective layer30 may be affixed to a selected portion that includes rear face 18 andsubstrate side surface 16 of substrate 12 and at least a portion ofsuperabrasive side surface 22 of superabrasive table 14. In at least oneembodiment, after protective layer 30 has been affixed to at least aportion of superabrasive element 10, a chamfered and/or rounded surface(e.g., superabrasive edge 24 illustrated in FIGS. 5A and 5B) may beformed between superabrasive face 20 and superabrasive side surface 22prior to leaching of superabrasive element 10.

After superabrasive element 10 has been leached, the remainingprotective layer 30 may be removed from superabrasive element 10. In atleast one embodiment, protective layer 30 may be substantially removedfrom superabrasive table 14 and/or substrate 12 using any suitabletechnique, including, for example, lapping and/or grinding. In someembodiments, following removal of protective layer 30, one or moresurfaces of superabrasive table 14 and/or substrate 12 may be processedto form a desired surface texture and/or finish using any suitabletechnique, including, for example, lapping, grinding, and/or otherwisephysically and/or chemically treating the one or more surfaces.

FIG. 7A is a cross-sectional side view of a portion of an exemplarysubstrate 12, a protective layer 30 formed over superabrasive element10, and an interface 31 formed between substrate 12 and protective layer30 according to at least one embodiment. According to at least oneembodiment, protective layer 30 may be affixed to superabrasive element10 at interface 31. For example, as illustrated in FIG. 7A, at least aportion of interface 31 may comprise a region extending betweenprotective layer 30 and substrate 12. According to some embodiments,interface 31 may comprise portions of both protective layer 30 andsuperabrasive element 10 (e.g., an alloy). For example, interface 31 maycomprise a hybrid layer or region formed by portions of protective layer30, substrate 12, and/or superabrasive table 14.

FIG. 7B is a magnified cross-sectional side view of a portion ofexemplary substrate 12, protective layer 30, and interface 31illustrated in FIG. 7A. As shown in FIG. 7B, interface 31 may include anintercalated hybrid layer formed between superabrasive element 10 andprotective layer 30. The portion of interface 31 illustrated in FIG. 7Bmay include a portion of protective layer 30 attached to a substrateside surface 16 of substrate 12.

Substrate 12 may include a plurality of projections, cavities,indentations, and/or other surface irregularities defined by and/oradjacent to a substrate side surface 16. According to at least oneembodiment, portions of protective layer 30 may be disposed betweenadjacent portions of substrate 12. For example, portions of protectivelayer 30 may at least partially fill cavities and/or indentationsdefined within substrate 12. Portions of protective layer 30 may also atleast partially surround projections extending from substrate 12.Accordingly, as shown in FIG. 7B, protective layer 30 and substrate 12may form an intercalated hybrid layer at interface 31, with theintercalated hybrid layer comprising alternating intermeshed portions ofprotective layer 30 and substrate 12.

An interface, such as interface 31, may also extend between protectivelayer 30 and a superabrasive table 14. Such an interface may include anintercalated hybrid layer comprising alternating, intermeshed portionsof protective layer 30 and superabrasive table 14. Superabrasive table14 may comprise numerous projections, cavities, indentations,interstices, and/or other surface irregularities defined by and/oradjacent to surface portions of superabrasive table 14. Such surfaceirregularities on portions of superabrasive table 14, such assuperabrasive side surface 22, may be defined by various superhardgrains (e.g., grains 38 as illustrated in FIG. 4) and/or by interstitialmaterials disposed between the superhard grains (e.g., interstitialmaterial 41 as illustrated in FIG. 4).

Interface 31 comprising an intercalated hybrid layer may be formed asprotective layer 30 is formed over superabrasive element 10 inaccordance with any of the techniques disclosed herein, withoutlimitation. An intercalated hybrid layer may be formed by applyingelevated temperatures and/or pressures to superabrasive element 10 andprotective layer 30. Elevated temperatures and/or pressures may causedeformation of protective layer 30, causing portions of protective layer30 to become intermeshed with portions of superabrasive element 10 toform an intercalated hybrid layer comprising intercalated portions ofprotective layer 30 and superabrasive element 10. In variousembodiments, superabrasive element 10 and protective layer 30 may beexposed to elevated temperatures and pressures during, for example,sintering of superabrasive table 14 and/or during molding of athermosetting resin to form protective layer 30 around superabrasiveelement 10.

In some examples, protective layer 30 may be formed on at least aportion of superabrasive element 10 by applying a liquid compositionand/or a powdered composition to an exterior of superabrasive element10. The liquid and/or powdered composition may be subjected to elevatedtemperatures and/or pressures, causing the composition to becomeintermeshed with portions of element 10. The liquid and/or powderedcomposition may at least partially conform to and become intermeshedwith surface irregularities defined by and/or adjacent to a surfaceportion of superabrasive element 10. Subsequently, the liquid and/orpowdered composition may be fixed and hardened to form a protectivelayer 30 that is intercalated with a portion of superabrasive element 10at interface 31.

According to some embodiments, protective layer 30 may comprise a solidelement that is placed adjacent to a particulate mixture (e.g.,particulate mixture 32 illustrated in FIG. 6A), and protective layer 30may be formed over superabrasive element 10 following sintering. In suchan example, protective layer 30 may comprise a material that ismalleable under HPHT sintering conditions, such that portions ofprotective layer 30 at least partially conform to surface irregularitiesdefined by and/or adjacent to a surface portion of superabrasive element10. An interface 31 comprising an intercalated hybrid layer formed byalternating portions of protective layer 30 and substrate 12 and/orsuperabrasive table 14 may enable protective layer 30 to be securelyfused to at least a portion of superabrasive element 10.

In at least one embodiment, forming an intercalated hybrid layer betweenprotective layer 30 and superabrasive element 10 may enable protectivelayer 30 to be securely affixed to superabrasive element 10, even insituations where there is a minimal amount of molecular bonding betweenprotective layer 30 and superabrasive element 10. In some examples,protective layer 30 may be mechanically secured to superabrasive element10 by the intercalated hybrid layer. For example, the alternating and/orintermeshing portions of protective layer 30 and superabrasive element10 forming the intercalated hybrid layer may mechanically fasten andhold protective layer 30 to superabrasive element 10.

Such an intercalated hybrid layer may also significantly increase theedge retention strength of protective layer 30, facilitating adhesion ofedges of protective layer 30 to superabrasive element 10 under a varietyof processing conditions. Accordingly, protective layer 30 may beprevented from separating from superabrasive element 10, allowingprotective layer 30 to be secured to superabrasive element 10, even inconfigurations where protective layer 30 does not completely surround aperiphery of superabrasive element 10. For example, protective layer 30may be securely affixed to superabrasive element 10 in various patterns,such as an alternating pattern. Additionally, protective layer 30 may besecurely affixed to superabrasive elements having variousnon-cylindrical and/or generally angular perimeters.

In at least one embodiment, because protective layer 30 is closelyformed to various surface irregularities in superabrasive element 10 atinterface 31, passageways between protective layer 30 and superabrasiveelement 10 allowing passage of a leaching solution may be significantlyreduced or eliminated. Accordingly, protective layer 30 may protectselected portions of superabrasive element 10 under a variety oftemperature and pressure conditions.

In some embodiments, portions of superabrasive element 10 that areaffixed and/or adjacent to protective layer 30 may be protected fromleaching, corrosion, and/or other damage under a relatively wide rangeof leaching conditions, including, for example, temperatures rangingbetween approximately 25° C. and approximately 250° C. and pressuresranging between approximately 1 bar and approximately 100 bar. In atleast one embodiment, protective layer 30 may also enable leaching ofsuperabrasive element 10 at temperatures below 25° C. or above 250° C.and/or at pressures below 1 bar and/or above 100 bar.

According to various embodiments, an interface 31 comprising anintercalated hybrid layer formed by protective layer 30 andsuperabrasive element 10 may minimize or eliminate gases trapped betweenprotective layer 30 and superabrasive element 10. Reducing oreliminating trapped gases between protective layer 30 and superabrasiveelement 10 may reduce the likelihood that portions of protective layer30 will become separated from superabrasive element 10. Accordingly,edges of protective layer 30 may be securely affixed to superabrasiveelement 10 and the formation of pockets between protective layer 30 andsuperabrasive element 10 due to the expansion of trapped gases may besignificantly reduced. Reducing the formation of pockets betweenprotective layer 30 and superabrasive element 10 may further reduce oreliminate the formation of passageways between protective layer 30 andsuperabrasive element 10 through which a leaching solution may migrate,thereby preventing undesired corrosion and/or damage to selectedportions of superabrasive element 10 during leaching.

FIGS. 8A-8C illustrate various patterns of protective layers formed overexemplary superabrasive elements according to various embodiments.Protective layer 30 may be formed over portions of superabrasive element10 in any suitable pattern, without limitation. Forming protective layer30 on superabrasive element 10 such that an intercalated hybrid layer(e.g., interface 31 in FIGS. 7A-7B) is formed may enable protectivelayer 30 to be securely affixed to superabrasive element 10 in variouspatterns. In some examples, protective layer 30 may be applied toexterior portions of superabrasive element 10 in a substantiallycontinuous layer, and subsequently, protective layer 30 may be removedfrom desired portions of super abrasive element 10 using any suitabletechnique, such as grinding and/or lapping. In additional embodiments,protective layer 30 may be patterned when it is formed on superabrasiveelement 10. For example, a protective layer 30 comprising athermosetting compound may be formed and molded to an exterior ofsuperabrasive element 10 using a mold configuration having a specifiedmolding pattern.

Forming protective layer 30 on superabrasive table 14 according tovarious patterns may cause superabrasive table 14 to be selectivelyleached when exposed to a leaching solution. Alternating leached andnon-leached regions of superabrasive table 14 may provide superabrasiveelement 10 with desired characteristics. For example, leached portionsof superabrasive table 14 may exhibit relatively higher heat resistanceand/or thermal stability and regions of superabrasive table 14 that arenot leached may exhibit a relatively higher degree of compression and arelatively higher impact resistance.

FIG. 8A is a top view of a patterned protective layer 30 formed oversuperabrasive face 20 of superabrasive element 10 according to at leastone embodiment. As illustrated in FIG. 8A, protective layer 30 may bearranged in an alternating pattern on superabrasive face 20, resultingin alternating leached and non-leached regions of superabrasive table 14following leaching. A superabrasive table 14 leached according to analternating pattern may, for example, exhibit both superior temperaturestability and superior impact strength.

FIGS. 8B and 8C are top views of protective layers 30 formed oversuperabrasive faces 20 according to at least one embodiment. Asillustrated in FIG. 8B, protective layer 30 may be formed over aselected region of a superabrasive table 14 near an outer edge portion(e.g., superabrasive edge 24 in FIG. 1) and a region of superabrasivetable 14 that is separated from the outer edge portion may be exposed toa leaching solution during leaching. As illustrated in FIG. 8C,protective layer 30 may be formed over a selected region ofsuperabrasive table 14 that is separated from the outer edge portion andan outer edge portion of superabrasive table 14 may be exposed to theleaching solution during leaching. Leaching superabrasive table 14according to a pattern where edge portions of superabrasive table 14 areleached differently from other portions of superabrasive table 14 mayresult in superabrasive table 14 exhibiting different characteristics atedge portions of superabrasive table 14, such as cutting regions ofsuperabrasive table 14 (e.g. superabrasive edge 24 in FIG. 1).

FIGS. 9A and 9B illustrate protective layers formed over selectedportions of exemplary superabrasive elements having various non-circularshapes according to various embodiments. Protective layer 30 may beformed over superabrasive elements having any suitable shape orgeometry, without limitation. Forming protective layer 30 oversuperabrasive element 10 such that an intercalated hybrid layer (e.g.,interface 31 in FIGS. 7A-7B) is formed may enable protective layer 30 tobe formed closely around and securely affixed to superabrasive elementshaving non-circular peripheries.

FIG. 9A illustrates a protective layer 30 formed over an exemplarysuperabrasive element 10 having multiple faces. For example, asillustrated in FIG. 9A, superabrasive element 10 may comprise asix-sided element having six faces, including superabrasive sidesurfaces 22A and 22B. Protective layer 30 may closely adhere to outerportions of superabrasive element 10, including side surfaces 22A and22B. Because, in this example, protective layer 30 is formed oversuperabrasive element 10 with an intercalated hybrid layer, protectivelayer 30 may be closely and securely affixed to superabrasive element10, including angular portions of superabrasive element 10 between sidesurfaces 22A and 22B.

FIG. 9B illustrates a protective layer 30 formed over an exemplarysuperabrasive element 10 having a non-circular periphery, such as anelliptical, oval, or other suitable non-circular and/or unevenperimeter. Because protective layer 30 is formed over superabrasiveelement 10 with an intercalated hybrid layer, protective layer 30 may beclosely and securely affixed to various surfaces of superabrasiveelement 10, including superabrasive side surface 22.

FIGS. 10A and 10B show exemplary superabrasive elements 10 that arepartially surrounded by a protective layer 30 and an additional layer.In particular, FIG. 10A is a cross-sectional side view of an exemplarysuperabrasive element 10 that is partially surrounded by a protectivelayer 30 and an intermediate layer 42 according to at least oneembodiment. As shown in FIG. 10A, intermediate layer 42 may comprise alayer of material disposed between at least a portion of protectivelayer 30 and superabrasive element 10. Similarly, FIG. 10B is across-sectional side view of an exemplary superabrasive element 10 thatis partially surrounded by a protective layer 30 and an outer layer 43according to at least one embodiment.

In at least one example, protective layer 30 may comprise a materialcapable of forming an intercalated hybrid layer with superabrasiveelement 10 and outer layer 43 may comprise a material having greaterchemical resistance to a leaching solution than protective layer 30. Asshown in FIG. 10B, outer layer 43 may comprise a layer of materialsurrounding at least a portion of protective layer 30 and superabrasiveelement 10. In various examples, both an intermediate layer 42 and anouter layer 43 may be formed around superabrasive element 10.

Intermediate layer 42 and/or outer layer 43 may comprise any suitablematerial or combination of materials, such as, for example, materialssuitable for use in protective layer 30, as disclosed above in referenceto FIGS. 5A-5D. Intermediate layer 42 and/or outer layer 43 may compriseany suitable metals, alloys, polymers, carbon allotropes, oxides,carbides, glass materials, ceramics, composites, and/or combination ofthe foregoing, without limitation. According to some examples,intermediate layer 42 and/or outer layer 43 may include, for example, afiller resin, sealant composition, thermosetting epoxy composition,and/or thermosetting silicone composition.

In some examples, intermediate layer 42 and/or outer layer 43 maycomprise a material that is relatively impermeable and/or non-reactivewith respect to an acidic, basic, and/or otherwise corrosive leachingsolution. Intermediate layer 42 and/or outer layer 43 may also comprisea material suitable for adhering to and/or sealing at least a portion ofsuperabrasive element 10. According to various examples, two or moreintermediate layers may be disposed between protective layer 30 andsuperabrasive element 10 and/or two or more outer layers may be disposedsurrounding protective layer 30.

Intermediate layer 42 and/or outer layer 43 may be formed oversuperabrasive element 10 and/or protective layer 30 using any suitabletechnique. For example, any suitable technique described herein forforming protective layer 30 on superabrasive element 10 may be used toform intermediate layer 42 and/or outer layer 43 on at least a portionof superabrasive element 10 and/or protective layer 30, withoutlimitation. In at least one example, intermediate layer 42 may be formedon and/or affixed to superabrasive element 10 prior to formingprotective layer 30 on intermediate layer 42 and/or superabrasiveelement 10. In various examples, outer layer 43 may be formed on and/oraffixed to superabrasive element 10 and/or protective layer 30 afterprotective layer 30 has been formed over superabrasive element 10 and/orintermediate layer 42.

In some embodiments, intermediate layer 42 and/or outer layer 43 may beformed on and/or affixed to superabrasive element 10 at substantiallythe same time that protective layer 30 is formed on intermediate layer42 and/or superabrasive element 10. For example, intermediate layer 42may be formed from a resin material placed between superabrasive element10 and a solid material used to form protective layer 30 (e.g., a metalcup surrounding at least a portion of superabrasive element 10). Theresin mixture may then be exposed to elevated heat and/or pressure,causing the resin mixture to form an intermediate layer 42 that isformed over superabrasive element 10 and/or protective layer 30.

FIGS. 11A-11C illustrate an exemplary configuration for formingprotective layer 30 and outer layer 33 on superabrasive element 10 (andsintering and/or leaching superabrasive element 10) according to atleast one embodiment. As illustrated in FIGS. 11A-11C, protective layer30 and outer layer 33 may be formed from sintering containers, such assintering cans used in sintering superabrasive element 10. Protectivelayer 30 and outer layer 33 may be fused to superabrasive element 10during sintering of superabrasive table 14. Outer layer 33 may be atleast partially removed from protective layer 30 and/or superabrasiveelement 10 during leaching of at least a portion of superabrasiveelement 10.

FIG. 11A is a cross-sectional side view of the exemplary sinteringconfiguration for forming a superabrasive element. Substrate 12 may bedisposed adjacent to a particulate mixture 32, and substrate 12 andparticulate mixture 32 may be surrounded by protective layer 30 andouter layer 33. In at least one embodiment, protective layer 30 andouter layer 33 may comprise a sintering container configured to surroundand hold substrate 12 and particulate mixture 32 during sintering.

Protective layer 30 and/or outer layer 33 may comprise any material orcombination of materials suitable for encasing substrate 12 andparticulate mixture 32 during sintering. Protective layer 30 and/orouter layer 33 may comprise a material or combination of materialscapable of withstanding high temperatures and/or pressures during HPHTsintering. For example, protective layer 30 and/or outer layer 33 maycomprise one or more refractory metals, including, for example, niobium,tantalum, molybdenum, tungsten, rhenium, chromium, vanadium, hafnium,and/or zirconium. Protective layer 30 and/or outer layer 33 may alsocomprise any other metallic and/or nonmetallic material suitable forencasing substrate 12 and/or particulate mixture 32 during sintering.

In at least one embodiment, protective layer 30 may comprise a materialthat is substantially inert and/or otherwise resistant to acids, bases,and/or other reactive compounds present in a leaching solution used toleach superabrasive element 10. For example, protective layer 30 maycomprise niobium, which may be substantially impervious to variousleaching solutions. Additionally, outer layer 33 may comprise a materialthat is soluble in certain leaching solutions and gas mixtures. Forexample, outer layer 33 may comprise zirconium, which may be dissolvedwhen exposed to leaching solutions, such as acidic leaching solutions.

Protective layer 30 and outer layer 33 may be disposed aroundsuperabrasive element 10 in any suitable configuration. For example, asillustrated in FIG. 11A, protective layer 30 may directly contactsubstrate 12 and/or particulate mixture 32. Outer layer 33 may bedisposed over an exposed portion of particulate mixture 32. Asillustrated in FIG. 11A, outer layer 33 may also overlap at least aportion of protective layer 30. For example, protective layer 30 andouter layer 33 may comprise sintering cans that are disposed overlappingeach other so that substrate 12 and particulate mixture 32 aresubstantially encased. In certain embodiments, outer layer 33 maycomprise a cover that covers particulate mixture 32 but does not overlapprotective layer 30 (e.g., cover 34 in FIG. 6A).

FIG. 11B is a cross-sectional side view of the exemplary sinteringconfiguration illustrated in FIG. 11A following sintering of particulatemixture 32 to form superabrasive table 14 and following subsequentleaching of superabrasive table 14. According to at least oneembodiment, following HPHT sintering, at least a portion of protectivelayer 30 may be bonded and/or otherwise affixed to superabrasive table14 and/or substrate 12 at interface 31.

According to at least one embodiment, following sintering, superabrasiveelement 10, which is surrounded by protective layer 30 and outer layer33, may be immersed in a suitable leaching solution. The leachingsolution may dissolve at least a portion of outer layer 33 so that atleast a portion of superabrasive table 14, such as superabrasive face20, is exposed to the leaching solution. After dissolution of outerlayer 33, protective layer 30 may remain affixed to both substrate 12and at least a portion of superabrasive table 14, as shown in FIG. 11B.In at least one example, following dissolution of outer layer 33,superabrasive element 10 may remain in the leaching solution for aspecified time or until superabrasive table 14 has been leached to adesired degree relative to superabrasive face 20.

FIG. 11C is a cross-sectional side view of the exemplary sinteringconfiguration illustrated in FIGS. 11A and 11B after protective layer 30has been removed from a portion of superabrasive element 10. Asillustrated in FIG. 11C, following dissolution of outer 33 and at leastpartial leaching of superabrasive table 14, protective layer 30 may beremoved from a portion of superabrasive side surface 22 of superabrasivetable 14 using any suitable technique, such a grinding. Superabrasivetable 14 may then be exposed to a leaching solution for a desired timeor until superabrasive table 14 has been leached to a desired depthrelative to superabrasive face 20 and/or superabrasive side surface 22.After superabrasive element 10 has been leached, the remaining portionof protective layer 30 may be removed from superabrasive element 10.

FIGS. 12, 13A, and 13B illustrate an exemplary technique for forming aprotective layer 44 over a superabrasive element 10 according to atleast one embodiment. FIG. 12 is a perspective view of an exemplarysuperabrasive element 10 and a protective layer 44 comprising aheat-shrink material. FIG. 13A is a cross-sectional side view of thesuperabrasive element 10 and the protective layer 44 illustrated in FIG.12.

As shown in FIGS. 12 and 13A, protective layer 44 may comprise a sleeveor tube sized and configured to surround at least a portion ofsuperabrasive element 10, including at least a portion of substrate 12and/or superabrasive table 14. In various embodiments, protective layer44 may comprise a heat-shrink sleeve or tube formed of a thermoplasticpolymer material. Examples of suitable thermoplastic materials include,without limitation, polyolefin, fluoropolymer, PVC, neoprene, siliconeelastomer, and/or synthetic rubber materials. Suitable fluoropolymersmay include, for example, PTFE, fluorinated ethylene propylene, and/orPVDF. In at least one example, protective layer 44 may comprise a TEFLON(DuPont, Wilmington, Del.) PTFE material.

In some embodiments, protective layer 44 may be configured to be formedover at least a portion of superabrasive element 10 following exposureto heat and/or pressure. For example, when protective layer 44 isexposed to an elevated temperature, protective layer 44 may shrinkand/or contract, causing protective layer 44 to more closely surroundsuperabrasive element 10, affixing protective layer 44 to superabrasiveelement 10. In some examples, when protective layer 44 is heated above athreshold temperature, monomers and/or polymers within protective layer44 may undergo a polymerization and/or crystallization process, causingprotective layer 44 to increase in density, thereby shrinking protectivelayer 44. In at least one embodiment, heat may be applied to protectivelayer 44 using any suitable heat source, including, for example, an ovenand/or a hot air gun.

FIG. 13B is a cross-sectional side view of the superabrasive element 10partially encased by the protective layer 44 illustrated in FIGS. 12 and13A. According to at least one embodiment, protective layer 44 mayconform to surface irregularities on at least a surface portion ofsuperabrasive element 10, frictionally securing protective layer 44 tosuperabrasive element 10. For example, portions of protective layer 44may closely surround protrusions on superabrasive element 10 and/or mayat least partially fill cavities defined within superabrasive element10. In some examples, an intercalated hybrid layer may be formed at aninterface between protective layer 44 and superabrasive element 10(e.g., interface 31 illustrated in FIGS. 7A and 7B). In variousembodiments, protective layer 44 may be heated to a temperature nearand/or above a melting point of protective layer 44 such that protectivelayer 44 melts and conforms to at least a portion of superabrasiveelement 10.

FIGS. 14 and 15 are perspective and top views, respectively, of anexemplary drill bit 45 according to at least one embodiment. Drill bit45 may represent any type or form of earth-boring or drilling tool,including, for example, a rotary drill bit. As illustrated in FIGS. 14and 15, drill bit 45 may comprise a bit body 46 having a longitudinalaxis 52. Bit body 46 may define a leading end structure for drillinginto a subterranean formation by rotating bit body 46 about longitudinalaxis 52 and applying weight to bit body 46. Bit body 46 may includeradially and longitudinally extending blades 47 with leading faces 48and a threaded pin connection 50 for connecting bit body 46 to a drillstring.

At least one cutting element 58 may be coupled to bit body 46. Forexample, as shown in FIG. 15, a plurality of cutting elements 58 may becoupled to blades 47. Cutting elements 58 may comprise any suitablesuperabrasive elements, without limitation. In at least one embodiment,cutting elements 58 may be configured according to previously describedsuperabrasive element 10 and/or superabrasive disc 28. In someembodiments, each cutting element 58 may include a superabrasive table60, such as a PCD table, bonded to a substrate 62.

Circumferentially adjacent blades 47 may define so-called junk slots 54therebetween. Junk slots 54 may be configured to channel debris, such asrock or formation cuttings, away from cutting elements 58 duringdrilling. Drill bit 45 may also include a plurality of nozzle cavities56 for communicating drilling fluid from the interior of drill bit 45 tocutting elements 58.

FIGS. 14 and 15 depict an example of a drill bit 45 that employs atleast one cutting element 58 comprising a superabrasive table 60fabricated and structured in accordance with the disclosed embodiments,without limitation. Drill bit 45 may additionally represent any numberof earth-boring tools or drilling tools, including, for example, corebits, roller-cone bits, fixed-cutter bits, eccentric bits, bicenterbits, reamers, reamer wings, and/or any other downhole tools comprisingsuperabrasive cutting elements and/or discs, without limitation.

The superabrasive elements and discs disclosed herein may also beutilized in applications other than cutting technology. For example,embodiments of superabrasive elements and/or discs disclosed herein mayalso form all or part of heat sinks, wire dies, bearing elements,cutting elements, cutting inserts (e.g., on a roller cone type drillbit), machining inserts, or any other article of manufacture, as knownin the art. According to some examples, superabrasive elements and/ordiscs, as disclosed herein, may be employed in medical deviceapplications, including, without limitation, hip joints, back joints, orany other suitable medical joints. Thus, superabrasive elements anddiscs, as disclosed herein, may be employed in any suitable article ofmanufacture that includes a superabrasive element, disc, or layer. Otherexamples of articles of manufacture that may incorporate superabrasiveelements as disclosed herein may be found in U.S. Pat. Nos. 4,811,801;4,268,276; 4,468,138; 4,738,322; 4,913,247; 5,016,718; 5,092,687;5,120,327; 5,135,061; 5,154,245; 5,460,233; 5,544,713; and 6,793,681,the disclosure of each of which is incorporated herein, in its entirety,by this reference.

In additional embodiments, a rotor and a stator, such as a rotor and astator used in a thrust bearing apparatus, may each include at least onesuperabrasive element according to the embodiments disclosed herein. Foran example, U.S. Pat. Nos. 4,410,054; 4,560,014; 5,364,192; 5,368,398;and 5,480,233, the disclosure of each of which is incorporated herein,in its entirety, by this reference, disclose subterranean drillingsystems that include bearing apparatuses utilizing superabrasiveelements as disclosed herein.

FIG. 16 is partial cross-sectional perspective view of an exemplarythrust-bearing apparatus 64 according to at least one embodiment.Thrust-bearing apparatus 64 may utilize any of the disclosedsuperabrasive element embodiments as bearing elements 70. Thrust-bearingapparatus 64 may also include bearing assemblies 66. Each bearingassembly 66 may include a support ring 68 fabricated from a material,such as steel, stainless steel, or any other suitable material, withoutlimitation.

Each support ring 68 may include a plurality of recesses 69 configuredto receive corresponding bearing elements 70. Each bearing element 70may be mounted to a corresponding support ring 68 within a correspondingrecess 69 by brazing, welding, press-fitting, using fasteners, or anyanother suitable mounting technique, without limitation. In at least oneembodiment, one or more of bearing elements 70 may be configuredaccording to previously described superabrasive element 10 and/orsuperabrasive disc 28. For example, each bearing element 70 may includea substrate 72 and a superabrasive table 74 comprising a PCD material.Each superabrasive table 74 may form a bearing surface 76.

Bearing surfaces 76 of one bearing assembly 66 may bear against opposingbearing surfaces 76 of a corresponding bearing assembly 66 inthrust-bearing apparatus 64, as illustrated in FIG. 16. For example, afirst bearing assembly 66 of thrust-bearing apparatus 64 may be termed a“rotor.” The rotor may be operably coupled to a rotational shaft. Asecond bearing assembly 66 of thrust-bearing apparatus 64 may be heldsubstantially stationary relative to the first bearing assembly 66 andmay be termed a “stator.”

FIG. 17 is a perspective view of a radial bearing apparatus 78 accordingto another embodiment. Radial bearing apparatus 78 may utilize any ofthe disclosed superabrasive element embodiments as bearing elements 84and 86. Radial bearing apparatus 78 may include an inner race 80positioned generally within an outer race 82. Inner race 80 may includea plurality of bearing elements 84 affixed thereto, and outer race 82may include a plurality of corresponding bearing elements 86 affixedthereto. One or more of bearing elements 84 and 86 may be configured inaccordance with any of the superabrasive element embodiments disclosedherein.

Inner race 80 may be positioned generally within outer race 82. Thus,inner race 80 and outer race 82 may be configured such that bearingsurfaces 85 defined by bearing elements 84 and bearing surfaces 87defined by bearing elements 86 may at least partially contact oneanother and move relative to one another as inner race 80 and outer race82 rotate relative to each other. According to various embodiments,thrust-bearing apparatus 64 and/or radial bearing apparatus 78 may beincorporated into a subterranean drilling system.

FIG. 18 is a partial cross-sectional perspective view of an exemplarysubterranean drilling system 88 that includes a thrust-bearing apparatus64, as shown in FIG. 16, according to at least one embodiment. Thesubterranean drilling system 88 may include a housing 90 enclosing adownhole drilling motor 92 (i.e., a motor, turbine, or any othersuitable device capable of rotating an output shaft, without limitation)that is operably connected to an output shaft 94.

The thrust-bearing apparatus 64 shown in FIG. 18 may be operably coupledto downhole drilling motor 92. A rotary drill bit 96, such as a rotarydrill bit configured to engage a subterranean formation and drill aborehole, may be connected to output shaft 94. As illustrated in FIG.10, rotary drill bit 96 may be a roller cone bit comprising a pluralityof roller cones 98. According to additional embodiments, rotary drillbit 96 may comprise any suitable type of rotary drill bit, such as, forexample, a so-called fixed-cutter drill bit. As a borehole is drilledusing rotary drill bit 96, pipe sections may be connected tosubterranean drilling system 88 to form a drill string capable ofprogressively drilling the borehole to a greater depth within asubterranean formation.

A first thrust-bearing assembly 66 in thrust-bearing apparatus 64 may beconfigured as a rotor that is attached to output shaft 94 and a secondthrust-bearing assembly 66 in thrust-bearing apparatus 64 may beconfigured as a stator. During a drilling operation using subterraneandrilling system 88, the rotor may rotate in conjunction with outputshaft 94 and the stator may remain substantially stationary relative tothe rotor.

According to various embodiments, drilling fluid may be circulatedthrough downhole drilling motor 92 to generate torque and effectrotation of output shaft 94 and rotary drill bit 96 attached thereto sothat a borehole may be drilled. A portion of the drilling fluid may alsobe used to lubricate opposing bearing surfaces of bearing elements 70 onthrust-bearing assemblies 66.

FIG. 19 illustrates an exemplary method 100 for processing apolycrystalline diamond element according to at least one embodiment. Asshown in FIG. 19, a protective layer may be formed over only a selectedportion of a polycrystalline diamond element (process 102). Thepolycrystalline diamond element may comprise a polycrystalline diamondtable (e.g., superabrasive table 14 of superabrasive element 10 andsuperabrasive disc 28 illustrated in FIGS. 1 and 2, respectively). Thepolycrystalline diamond element may also comprise a substrate bonded tothe polycrystalline diamond table. For example, a polycrystallinediamond table may be bonded to a tungsten carbide substrate (e.g.,superabrasive element 10 illustrated in FIG. 1).

The selected portion of the polycrystalline diamond element may compriseat least a portion of a surface of the substrate and at least a portionof a surface of the polycrystalline diamond table. For example, theprotective layer may be affixed to a selected portion of thepolycrystalline diamond element that includes the substrate and aportion of the polycrystalline diamond table near the substrate (e.g.,superabrasive element 10 surrounded by protective layer 30 illustratedin FIGS. 5A-5C). The protective layer may comprise any suitablematerial, including metals, alloys, polymers, carbon allotropes, oxides,carbides, glass materials, ceramics, composites, and/or any combinationof the foregoing, without limitation.

The protective layer may be affixed to the polycrystalline element inany suitable manner, without limitation. In some examples, theprotective layer may be affixed or fused to the polycrystalline diamondelement at an interface between the protective layer and thepolycrystalline diamond element (e.g., interface 31 illustrated in FIGS.7A and 7B). According to at least one embodiment, the interface betweenthe protective layer and the polycrystalline diamond element may includean intercalated hybrid layer comprising portions of the protective layerand portions of the polycrystalline diamond element. In someembodiments, an outer layer may be formed on at least a portion of anouter surface of the protective layer (e.g., outer layer 43 illustratedin FIG. 10).

At least a portion of the polycrystalline diamond element may be exposedto a leaching solution such that the leaching solution contacts anexposed surface region of the polycrystalline diamond table and at leasta portion of the protective layer (process 104). The polycrystallinediamond material may be exposed to the leaching solution in any suitablemanner, such as, for example, by submerging at least a portion of thepolycrystalline diamond material in the leaching solution. Theprotective layer may be substantially impermeable to the leachingsolution. In some examples, the protective layer may comprise asubstantially inert material or a material that is otherwisesubstantially non-reactive with respect to the leaching solution.

In some embodiments, an edge portion of the polycrystalline diamondtable may be chamfered. For example, the edge portion of thepolycrystalline diamond table may be chamfered using a grinder after theprotective layer is affixed to the polycrystalline diamond element andbefore the polycrystalline diamond element is exposed to the leachingsolution. In at least one embodiment, a reference mark may be placed ona portion of the polycrystalline diamond element. A centerless grinder(e.g., a centerless CNC grinding machine) may then grind the edgeportion of the polycrystalline diamond table utilizing the referencemark to locate the edge portion. The reference mark may enable thecenterless grinder to form a relatively even and consistent chamferedand/or rounded edge around the polycrystalline diamond table.

After the polycrystalline diamond element has been leached, theprotective layer may be removed from at least a portion of the selectedportion of the polycrystalline diamond element. For example, theprotective layer may be substantially removed from the polycrystallinediamond table and the substrate using any suitable technique, such as,for example, lapping and/or grinding. In some embodiments, followingremoval of the protective layer, one or more surfaces of thepolycrystalline diamond table and/or the substrate may be processed toform a desired surface texture and/or finish using any suitabletechnique, including, for example, lapping, grinding, and/or otherwisephysically and/or chemically treating the one or more surfaces.

FIG. 20 illustrates an exemplary method 110 for manufacturing apolycrystalline diamond element according to at least one embodiment. Asshown in FIG. 20, the method may comprise forming a protective layerover only a selected portion of a polycrystalline diamond element duringsintering of a polycrystalline diamond table of the polycrystallinediamond element (process 112).

In at least one embodiment, a particulate mixture comprising diamondparticles may be disposed adjacent to a substrate and the protectivelayer (e.g., particulate mixture 32 disposed adjacent to substrate 12and protective layer 30, as illustrated in FIG. 6A). The particulatemixture may then be HPHT sintered to form the polycrystalline diamondtable such that the protective layer is formed on at least a portion ofa surface of the polycrystalline diamond table (e.g., superabrasivetable 14 disposed adjacent to substrate 12 and protective layer 30, asillustrated in FIGS. 6B and 6C). At least a portion of thepolycrystalline diamond element may then be exposed to a leachingsolution such that the leaching solution contacts an exposed surfaceregion of the polycrystalline diamond table and at least a portion ofthe protective layer (process 114).

FIG. 21 illustrates an exemplary method 120 for processing apolycrystalline diamond element according to various embodiments. Asshown in FIG. 21, at least a portion of a polycrystalline diamondelement may be surrounded with a protective heat-shrink layer (e.g.,protective layer 44 illustrated in FIG. 12) (process 122). Theprotective heat-shrink material may be exposed to a temperature at whichthe heat-shrink material contracts against a selected portion of thepolycrystalline diamond element (process 124). At least a portion of thepolycrystalline diamond element may then be exposed to a leachingsolution such that the leaching solution contacts an exposed surfaceregion of the polycrystalline diamond table and at least a portion ofthe protective layer (process 126).

FIG. 22 illustrates an exemplary method 130 for processing apolycrystalline diamond element according to various embodiments. Asshown in FIG. 22, a protective layer and an intermediate layer (e.g.,intermediate layer 42 illustrated in FIG. 10A) may be formed on aselected portion of a polycrystalline diamond element (process 132). Atleast a portion of the polycrystalline diamond element may then beexposed to a leaching solution such that the leaching solution contactsan exposed surface region of the polycrystalline diamond table and atleast a portion of the protective layer (process 134).

Example 1

A tungsten carbide substrate and a particulate diamond mixture wereplaced adjacent to each other in a niobium can. A niobium cap wascrimped onto the niobium can. The niobium can containing the substrateand the particulate diamond mixture was then placed in a HPHT press andthe particulate diamond mixture was sintered to form a PCD cuttingelement comprising a PCD table.

Following the sintering process, the PCD table was observed to be fusedto the tungsten carbide substrate and the niobium can was observed to befused to both the tungsten carbide substrate and the PCD table. Aportion of the niobium can was removed from a front face of the PCDtable through lapping. Additionally, a portion of the niobium can wasremoved from a side portion of the PCD table adjacent to the front face,leaving the entire tungsten carbide substrate and a portion of the PCDtable adjacent to the substrate encased by the niobium can.

The PCD cutting element encased by the niobium can was then placed in a1.5 M nitric acid solution to be leached. The PCD cutting element wasexposed to the solution for 24 hours at a temperature of 110° C. The PCDcutting element was removed from the solution. Following leaching, therewas no evidence of dissolution of the substrate or other damage to thesubstrate of the leached PCD cutting element.

Example 2

A niobium can was tightly swaged around a PCD cutting element having atungsten carbide substrate and a chamfered PCD table. The niobium canencased the entire substrate and a portion of the PCD table such thatthe front surface and the chamfered region of the PCD table wereexposed.

The PCD cutting element encased by the niobium can was then leached in a1.5 M nitric acid solution for 24 hours at a temperature of 110° C., asdetailed in Example 1. Following leaching, there was no evidence ofdissolution of the substrate or other damage to the substrate of theleached PCD cutting element.

Example 3

A niobium can was tightly swaged around a PCD cutting element having atungsten carbide substrate and a chamfered PCD table, as detailed inExample 2. The PCD cutting element encased by the niobium can wasexposed to a temperature of 180° C. and a vacuum pressure of 20 in Hg ina vacuum oven for about 12 hours.

The PCD cutting element encased by the niobium can was then leached in a1.5 M nitric acid solution for 24 hours at a temperature of 110° C., asdetailed in Example 1. Following leaching, there was no evidence ofdissolution of the substrate or other damage to the substrate of theleached PCD cutting element.

Example 4

A niobium can was placed around a PCD cutting element having a tungstencarbide substrate and a chamfered PCD table. An EPOMET epoxy resinmaterial was disposed in the can between the PCD cutting element and theniobium can. The can was tightly swaged around the PCD cutting elementand the resin material. The niobium can and resin encased the substrateand a portion of the PCD table, leaving the front surface and thechamfered region of the PCD table exposed.

The PCD cutting element encased by the resin material and the niobiumcan was then leached in a 1.5 M nitric acid solution for 24 hours at atemperature of 110° C., as detailed in Example 1. Following leaching,there was no evidence of dissolution of the substrate or other damage tothe substrate of the leached PCD cutting element.

Example 5

An EPOMET epoxy resin was disposed around a PCD cutting element having atungsten carbide substrate and a chamfered PCD table. The EPOMET epoxyresin was mounted to the PCD cutting element and cured using a BUEHLERcompression mounting press (Buehler, Ltd., Lake Bluff, Ill.) at apressure of about 3300 psi and a temperature of 150° C. to form across-linked polymer layer. The polymer layer and cutting element werethen cooled under elevated pressure, and the pressure was subsequentlyreduced to atmospheric pressure.

Following the mounting and curing process, the polymer layer wasobserved to be fused to both the tungsten carbide substrate and the PCDtable with excellent edge retention. The polymer layer surrounded theentire tungsten carbide substrate and a portion of the PCD tableadjacent to the substrate, leaving the front surface and the chamferedregion of the PCD table exposed.

The PCD cutting element encased by the polymer layer was then leached ina 1.5 M nitric acid solution for 24 hours at a temperature of 110° C.,as detailed in Example 1. Following leaching, there was no evidence ofdissolution of the substrate or other damage to the substrate of theleached PCD cutting element.

The preceding description has been provided to enable others skilled inthe art to best utilize various aspects of the exemplary embodimentsdescribed herein. This exemplary description is not intended to beexhaustive or to be limited to any precise form disclosed. Manymodifications and variations are possible without departing from thespirit and scope of the instant disclosure. It is desired that theembodiments described herein be considered in all respects illustrativeand not restrictive and that reference be made to the appended claimsand their equivalents for determining the scope of the instantdisclosure.

Unless otherwise noted, the terms “a” or “an,” as used in thespecification and claims, are to be construed as meaning “at least oneof.” In addition, for ease of use, the words “including” and “having,”as used in the specification and claims, are interchangeable with andhave the same meaning as the word “comprising.”

What is claimed is:
 1. A method of processing a polycrystalline diamondelement, the method comprising: forming a protective layer over aselected portion of a polycrystalline diamond element, thepolycrystalline diamond element comprising a polycrystalline diamondtable comprising: a superabrasive face; a superabrasive side surface; achamfer extending between the superabrasive face and the superabrasiveside surface; exposing at least a portion of the polycrystalline diamondelement to a leaching solution such that the leaching solution contactsan exposed surface region of the polycrystalline diamond table and atleast a portion of the protective layer; wherein: a portion of thesuperabrasive side surface is covered by the protective layer; theprotective layer is not formed over the chamfer.
 2. The method of claim1, wherein: the polycrystalline diamond element further comprises asubstrate bonded to the polycrystalline diamond table; at least aportion of a surface of the substrate is covered by the protectivelayer.
 3. The method of claim 1, wherein the protective layer comprisesa substantially inert material.
 4. The method of claim 1, wherein theprotective layer is substantially impermeable to the leaching solution.5. The method of claim 1, wherein forming the protective layer over theselected portion of the polycrystalline diamond element comprisesexposing the protective layer to an elevated temperature of about 50° C.or higher and an elevated pressure of about 1000 psi or higher.
 6. Themethod of claim 1, wherein an intercalated hybrid layer is formed at aninterface between the protective layer and the polycrystalline diamondelement.
 7. The method of claim 1, wherein the protective layercomprises a metallic material.
 8. The method of claim 7, wherein themetallic material comprises at least one of: a refractory metal; aprecious metal; a steel alloy; a steel derivative alloy.
 9. The methodof claim 1, wherein the protective layer comprises a thermoplasticmaterial.
 10. The method of claim 1, wherein the protective layercomprises a glass sealant.
 11. The method of claim 1, wherein theprotective layer comprises graphite.
 12. The method of claim 1, wherein:the protective layer comprises a thermosetting material; forming theprotective layer over the selected portion of the polycrystallinediamond element comprises curing the thermosetting material.
 13. Themethod of claim 1, further comprising, prior to exposing at least aportion of the polycrystalline diamond element to the leaching solution:forming the protective layer over the selected portion of thepolycrystalline diamond element; partially removing the protective layerfrom the selected portion of the polycrystalline diamond element. 14.The method of claim 1, further comprising forming an outer layer on atleast a portion of an outer surface of the protective layer.
 15. Themethod of claim 1, wherein a portion of the superabrasive side surfaceproximate to the chamfer is covered by the protective layer.
 16. Apolycrystalline diamond element, comprising: a polycrystalline diamondtable comprising: a superabrasive face; a superabrasive side surfaceextending around an outer periphery of the superabrasive face; a chamferextending between the superabrasive face and the superabrasive sidesurface; wherein: the polycrystalline diamond table comprises a leachedvolume extending from the superabrasive face to a portion of the chamferproximate to the superabrasive side surface; the leached volume does notsubstantially extend along the superabrasive side surface.
 17. Thepolycrystalline diamond element of claim 16, further comprising asubstrate bonded to the polycrystalline diamond table.
 18. Thepolycrystalline diamond element of claim 16, wherein the polycrystallinediamond table further comprises a transition region between the leachedvolume and an unleached volume of the polycrystalline diamond table. 19.The polycrystalline diamond element of claim 18, wherein the transitionregion extends to an intersection between the chamfer and thesuperabrasive side surface.